Multiple-wavelength light emitting device and electronic apparatus

ABSTRACT

An efficient multiple-wavelength light emitting device is provided. This multiple-wavelength light emitting device comprises a light emitting layer  4  for emitting light containing wavelength components to be output, a negative electrode  5  that is positioned at the back surface of the light emitting layer and that transmits at least a portion of the light, reflecting layers  7 R,  7 G, and  7 B, positioned at the back surface of the negative electrode, for reflecting, of the light emitted through the negative electrode to the back surface, light having specific wavelengths, which reflecting layers are stacked up in order perpendicularly to the light axis, in correspondence with the wavelengths of the light to be reflected, thus configuring a reflecting layer group  7 . In the direction perpendicular to the light axis, divisions are made in any of at least two or more light emission regions which reflect light of different wavelengths. In each light emission region, the distance between the reflecting surface of the reflecting layer  7  on the semi-transparent side and the reflecting surface in the semi-reflecting layer  2  is adjusted in this configuration so that it becomes a resonating optical path length for the light that is emitted in the light emission region.

FIELD OF THE INVENTION

This invention relates to light emitting devices capable of emittinglight of a plurality of colors and suitable for use as organicelectro-luminescence (EL) devices, and particularly to the improvementof reflecting layers therein.

DESCRIPTION OF THE RELATED ART

Art is known for combining reflecting layers with multi-layer dielectricfilms laminated in alternating layers having different refractiveindexes and thereby reflecting light of specific wavelengths. In theShingaku Giho OME 94-79 (March, 1995), pp 7-12, there is a discussion onhow to emit multiple colors of light using a micro resonance structurebased on such a multi-layer dielectric film. According to thisliterature, by adjusting the positions of the light emitting layers andthe reflecting layers where reflection occurs in the micro resonancestructure, it is possible to output resonant light of any wavelengthcontained in the light emitting layers.

In Japanese Patent Application Laid-Open No. H6-275381/1994 (gazette),for example, a light emitting device having the laminar structurediagrammed in FIG. 9 is set forth. This light emitting device comprisesa transparent substrate 100, a micro resonance structure 102, a positiveelectrode 103, a hole transport layer 104, an organicelectro-luminescence (EL) layer 105, and a negative electrode 106. Ofthese, the thickness of the positive electrode 103 is variedrespectively to select the wavelength of the light that resonates.Aluminum or alkali metals are used as the material for the negativeelectrode.

In a conventional electro-luminescence device, the negative electrode isideally designed so that it completely reflects light. In actualpractice, the negative electrode has been designed at times so that itis made as thin as possible to make the relative drive resistance of theEL-layer smaller.

When the negative electrode is formed thinly, however, the reflectancethereof is not always sufficient, whereupon some of the light leaks outto the back side of the electro-luminescence device without beingreflected. Light utilization has thus been rather low compared to theideal reflecting layer where complete reflection is assumed. When amirror formed by a micro resonance structure such as cited in JapanesePatent Application No. H6-275381/1994 is positioned on the front surface(light output side) of the EL layer and wavelength selectivity therebyraised, the amount of light returning to the light emitting layer sidefrom this mirror is increased. In a conventional device having such astructure as this, the reflectance of the negative electrode at the backsurface of the EL layer is low, wherefore the light utilization factordeclines significantly, which is a problem.

If only light reflecting efficiency is to be considered, there arematerials known which exhibit high reflectance. However, there arerestrictions on the materials which can be used for the negativeelectrode in an electro-luminescence device, such as energy level, andit has not been possible to use negative electrodes of high reflectancein conventional devices.

Returning the light that leaks out with a reflecting mirror isconceivable, but no suitable reflecting mirror has been devised that issuitable for a thin-film device.

SUMMARY OF THE INVENTION

A first object of the present invention is to provide amultiple-wavelength light emitting device that can emit light in aplurality of wavelengths with higher efficiency than conventionally.

A second object of the present invention is to provide amultiple-wavelength light emitting device that has higher efficiencythan conventionally for multiple wavelengths and that has a simplerstructure.

A third object of the present invention is to provide an electronicapparatus that can emit light in a plurality of wavelengths with higherefficiency than conventionally.

The present invention is a multiple-wavelength light emitting device foremitting light in a plurality of different wavelengths, comprising:

(1) light emission means for emitting light containing wavelengthcomponents to be output,

(2) a semi-transparent layer that transmits at least a portion of thelight, placed at the back surface of the light emission means,

(3) a reflecting layer group provided on a first surface side of thelight emission means, with the semi-transparent layer intervening,wherein reflecting layers that reflect light having specific wavelengthsof the light ejected to (or transmitted towards) the first surface sidefrom the light emission means via the semi-transparent layer arelaminated in order in the direction of the light axis, which is in thedirection of light advance, in correspondence with wavelengths of lightto be output, and

(4) a semi-reflecting layer group provided on a second surface side inopposition to the first surface of the light emission means, whereinsemi-reflecting layers that reflect a portion of light having specificwavelengths of the light ejected to the second surface side from thelight emission means and transmit the remainder thereof are laminated inorder in the direction of the light axis, which is in the direction oflight advance, in correspondence with the wavelengths of light to beoutput.

In two or more light emission regions wherein the output lightwavelength differs, the distance between the reflecting surface forlight from the light emission means in a reflecting layer in thereflecting layer group that reflects light of the wavelength output inthat light emission region and the reflecting surface for light from thelight emission means in a semi-reflecting reflecting layer in thesemi-reflecting layer group that reflects a portion of light of thewavelength output in that light emission region is adjusted so that itbecomes a resonating optical path length for light ejected from thatlight emission region.

As based on the configuration described in the foregoing, the light thatis ejected to the second surface (back surface) from the light emissionmeans and passes through the semi-transparent layer to leak out isreflected by the action of the reflecting layer group, again passesthrough the semi-transparent layer, and is ejected to the first surface(front surface) side of the light emitting device. By adjusting thedistance between the semi-reflecting layer and the reflecting layer, thewavelength of the light output from that light emission region isdetermined. In that light emission region, other reflecting layers thatare optimized for light having wavelengths other than the wavelength ofthe light output do no more than act equally in every light emissionregion as semi-transparent layers simply having a constant attenuationfactor, wherefore it is possible to maintain light volume balancebetween light of multiple wavelengths.

The terms employed in this patent application are now defined. The term“light emission means” is not limiting, but it is at least necessarythat wavelength components for the light that is to be output becontained. It is desirable that the “reflecting layers” form a flatplane, but it does not necessarily have to be a uniform plane. By “lightemission region” is meant a region for outputting light having somewavelength dispersion, meaning that light is output in wavelengths thatdiffer for each light emission region. The “wavelengths” include notonly wavelengths in the so-called visible light region but allwavelengths of a wider range including ultraviolet and infraredradiation. “Reflecting layers” include such structures as simplecompletely reflecting mirrors, half mirrors, and polarizing panels inaddition to interference-causing laminar structures wherein multiplelayers of film having different refractive indexes are laminated.“Semi-reflecting layers” include structures such as half mirrors andpolarizing panels in addition to interference-causing laminar structureswherein multiple layers of film having different refractive indexes arelaminated. By “optical path length” is meant a distance corresponding tothe product of the refractive index and thickness of a medium.

The thickness of the semi-transparent layers described in the foregoingis adjusted so that the phase of the light that, after being reflectedby the reflecting layer group, again passes through thatsemi-transparent layer and is ejected to (or transmitted towards) thesecond surface side of the light emission means coincides with the phaseof the light that is directly ejected to the second surface side of thelight emission means.

It is here desirable that an adjustment be made so that the followingrelationship is satisfied.

Σ(ni·di)=m·λ/2

where, in a light emission region wherein light of wavelength λ isejected, ni is the refractive index in each layer that exists betweenthe point of light emission in the light emission means and the lightreflecting surface of the light reflecting layer for light of wavelengthλ in the light reflecting layer group, di is the thickness thereof, andm is a natural number.

In the present invention, for example, a gap adjusting layer is providedbetween the semi-transparent layer and the reflecting layer group foradjusting the distance between the reflecting surface for the light fromthe light emission means in the light reflecting layer and thereflecting surface for the light from the light emission means in thesemi-reflecting layer.

The reflecting layer group described in the foregoing is configured, forexample, with multiple types of reflecting layer corresponding to thewavelengths of multiple kinds of light of different wavelength separatedbetween the light emission regions.

Specifically, the reflecting surfaces for light from the light emissionmeans in the reflecting layers in the reflecting layer group are locatedat different positions in the thickness dimension for each lightemission region.

Specifically, in a light emission region where light of wavelength λ isejected, the distance L between a reflecting surface for light from thelight emission means in the reflecting layer and the reflecting surfacefor light from the light emission means in the semi-reflecting layer isadjusted so that the following relationships are satisfied.

L=Σdi

Σ(ni·di)=m·λ/2

where ni is the refractive index of the i'th substance between thesereflecting surfaces, di is the thickness thereof, and m is a naturalnumber.

It is preferable that, in the reflecting layer group described above,reflecting layers reflecting light of longer wavelength are placed onthe light emission means side.

When reflecting layers are configured with multi-layer dielectric films,the reflective layers making up the reflecting layer group noted aboveare configured so that two layers of different refractive index arealternately stacked up.

The reflecting layers are adjusted so that the following relationship issatisfied.

n 1·d 1≈n 2·d 2≈(¼+m/2)·λ

where n1 is the refractive index of one layer of the two layers havingdiffering refractive indexes, d1 is the thickness thereof, n2 is therefractive index of the other layer, d2 is the thickness thereof, λ isthe wavelength of light reflected in the reflecting layer thereof, and mis 0 or a natural number.

The surfaces on the reflecting layer group side of the semi-transparentlayers noted above are formed so that they are in the same plane in alllight emission regions.

In the reflecting layer group noted above, for example, multiple typesof reflecting layers corresponding to the wavelengths of light ofmultiple different wavelengths may be laminated uniformly without beingseparated between light emission regions.

In the reflecting layer group noted in the foregoing, for example,spacers are provided between the reflecting layers for adjusting theoptical path length between the reflecting surface for light from thelight emission means in the reflecting layer and the reflecting surfacefor light from the light emission means in the semi-reflecting layer.

In the reflecting layer group noted above, for example, in order toadjust the optical path length from the reflecting surface for lightfrom the light emission means in the reflecting layers noted above tothe reflecting surface for the light on the light emission means side inthe semi-reflecting layers noted above, the thickness of any one layerin the laminar structure of layers having different refractive indexesconfiguring those reflecting layers is altered.

As one example, there are cases where a plurality of types of lightemission means for emitting relatively light having a plurality ofwavelengths associated with the light emission regions noted above isprovided so as to correspond with those light emission regions.

As another example, there are cases where light emission means capableof emitting light having wavelength components associated with all ofthe light emission regions noted in the foregoing is provided in commonin those light emission regions.

In one specific configuration the light emission means noted above is anorganic electro-luminescence layer sandwiched between electrodes, withthe electrode provided at the first surface thereof being made thesemi-transparent layer noted above.

These light emission means may be provided with an electron transportlayer and/or a hole transport layer.

The present invention is a multiple-wavelength light emitting device foremitting a plurality of light types having different wavelengths,comprising an organic electro-luminescence layer for emitting lightcontaining the wavelength components to be output, and an electrode forreflecting the light ejected to (or transmitted towards) the firstsurface of that organic electro-luminescence layer, positioned at thefirst surface of the organic electro-luminescence layer. The presentinvention is also a multiple-wavelength light emitting device that ischaracterized in that the electrode is configured of one substanceselected from a group made up of diamond, boron nitride, or aluminumnitride.

The present invention is an electronic apparatus comprising themultiple-wavelength light emitting device of the present inventiondescribed above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of the layer structure in amultiple-wavelength light emitting device in a first embodiment of thepresent invention;

FIG. 2 is a diagram for explaining interference conditions in reflectinglayers;

FIG. 3 is a cross-sectional diagram of the layer structure in amultiple-wavelength light emitting device in a second embodiment of thepresent invention;

FIG. 4 is a cross-sectional diagram of the layer structure in amultiple-wavelength light emitting device in a third embodiment of thepresent invention;

FIG. 5 is a cross-sectional diagram of the layer structure in amultiple-wavelength light emitting device in a fourth embodiment of thepresent invention;

FIG. 6 is a cross-sectional diagram of the layer structure in amultiple-wavelength light emitting device in a fifth embodiment of thepresent invention;

FIG. 7 is a cross-sectional diagram of the layer structure in amultiple-wavelength light emitting device in a sixth embodiment of thepresent invention;

FIG. 8 is a cross-sectional diagram of the layer structure in amultiple-wavelength light emitting device in a seventh embodiment of thepresent invention;

FIG. 9 is a cross-sectional diagram of the layer structure in aconventional light emitting device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are now described whilereferencing the drawings.

Embodiment 1

A first embodiment of the present invention relates to a basic structurefor a high-efficiency multiple-wavelength light emitting device capableof emitting three primary colors as necessary for color displays, andcapable of returning light that leaks out to the back surface to thefront surface. In FIG. 1 is diagrammed the layer structure of themultiple-wavelength light emitting device in the first embodiment. Thelower side in the drawing is the side (front surface) on which isejected light for the second surface of the light emitting device, whilethe upper side in the drawing is the side (back surface) on which lightis ejected for the first surface of the light emitting device.

This multiple-wavelength light emitting device comprises a substrate 1,a semi-reflecting layer group 2, a positive electrode 3, a lightemitting layer 4, a negative electrode 5, a gap adjustment layer 6, anda reflecting layer group 7. The layer structure in the present inventionpertains to the light emitting layer 4, the negative electrode 5, thegap adjustment layer 6, and the reflecting layer group 7. Theconfiguration of the front surface side of the light emission layer 4 isonly given as an example and may comprise another structure.

This multiple-wavelength light emitting device is divided into two ormore light emission regions where light of different wavelengths isreflected in the dimension perpendicular to the light axis. In thisembodiment, where it is assumed that the primary colors are red (R),green (G), and blue (B), three light emission regions are comprised,namely light emission region A_(R) which reflects and ejects red andtransmits light of wavelength λ_(R), light emission region A_(G) whichreflects and ejects green light of wavelength λ_(G), and light emissionregion A_(B) which reflects and ejects blue light of wavelength λ_(B).

Light emission layers 4R, 4G, and 4B are light emission means foremitting light containing the wavelength components to be output, formedrespectively of an organic EL material. The organic EL material used foreach emits a relatively large amount of light containing lightcomponents of a wavelength associated with one of the light emissionregions. Any of the materials researched and developed as an organicelectro-luminescence device material can be used appropriately for thematerials in these light emitting layers, such as those, for example,cited in Japanese Patent Application Laid-Open No. H10-163967/1998 orJapanese Patent Application Laid-Open No. H8-248276/1996. Morespecifically, the material for the red light emitting layer 4R may be acyano-polyphenylene vinylene precursor,2-1,3′,4′-dihydroxy-phenyl-3,5,7-trihydroxy-1-benzo-polybariumperchlorate,- or PVK, doped with DCM1. The material for the green lightemitting layer 4G may be a polyphenylene vinylene precursor,2,3,6,7-tetrahydro-11-oxo-1H,5H,11H-(1) benzopyrano[6,7,8-ink jetrecording head]-quinolidine-10-carbolic acid, or PVK, doped withquotamine 6. And the material for the blue light emitting layer 4B maybe an aluminum quinolinol complex, pyrazoline dimer,2,3,6,7-tetrahydro-9-methyl-11-oxo-1H,5H,11H-(1)benzopyrano[6,7,8-inkjet recording head]-quinolidine, distilled derivative, or PVK doped with1,1,4,4-triphenyl-1,3-butadiene.

Whether the light emisssion point lies at the center position of thelight emission layer changes depending on whether or not an electrictransport layer is present. The thickness of each light emitting layeris determined according to the relationship between the light emissionwavelength and the negative electrode that forms the reflecting surface.

The negative electrode 5 is positioned at the back surface of the lightemitting layer and functions as a semi-transparent layer to transmit atleast a portion of the light. In order to cause this to function as thenegative electrode in an organic EL device, either a metal, alloy, orelectrically conductive compound having a small work function (4 eV orlower), or a mixture thereof, is used. The configuration in thisembodiment, in particular, makes it possible for light leaking out tothe back surface to be returned by a reflecting layer, wherefore thereis no need to consider light reflectance. Specific examples of negativeelectrode materials include sodium, sodium-potassium alloys, magnesium,lithium, magnesium/copper mixtures, magnesium/silver mixtures,magnesium/aluminum mixtures, magnesium/indium mixtures,aluminum/aluminum oxide mixtures, indium, lithium/aluminum mixtures,rare earth metals or halides. The negative electrode 5, as asemi-transparent layer, may be a single layer or a laminar structuremade up of a plurality of layers.

It is desirable that the thickness of the negative electrode 5 describedin the foregoing be adjusted so that the phase of the light that isreflected by the reflecting layer group 7, that passes again through thesemi-transparent layer, and that is ejected to the front surface of thelight emitting layer 4 be made to coincide with the phase of the lightthat is directly ejected to the front surface of that light emittinglayer 4. This adjustment is made, for example, so that, in a lightemission region that causes light of wavelength λ to be ejected, thefollowing relationship is satisfied.

Σ(ni·di)=m·λ/2  Eq. 1

where ni is the refractive index, respectively, of each layer (or ofeach layer substance in cases where the negative electrode comprises aplurality of layers) present between the light emission point in thelight emission means described earlier and the reflecting surface in thereflecting layer for light of wavelength λ in the reflecting layer groupdescribed earlier, di is the thickness thereof, respectively, and m is anatural number. It is preferable, however, that the relationship inEquation 1 above be satisfied also in cases where ni is the refractiveindex, respectively, of each layer existing between the light emissionpoint in the light emission means and the reflecting surface for lightof wavelength λ, di is the thickness thereof, respectively, and m is anatural number.

The gap adjustment layer 6 is a layer provided for adjusting the opticalpath length for the reflected light. It may be of any material so longas it transmits light. For the material of the gap adjustment layer 6,it is possible to use a light-transmissive organic substance or aninorganic substance such as SiO₂, Si₃N₄, TiO₂, or some other dielectric.

The thickness of the gap adjustment layer 6 is adjusted so that, in eachlight emission region, the distance between the reflecting surface onthe light emitting layer side of the reflecting layer and the reflectingsurface on the light emitting layer side of the semi-reflecting layerbecomes an optical path length (L_(R), L_(G), L_(B)) wherein lightreflected in each light emission region resonates.

It is desirable that the distance L between the reflecting surface onthe negative electrode 5 side of the reflecting layer 7 that reflectslight of wavelength λ and the reflecting surface on the negativeelectrode side of the semi-reflecting layer 2, in the light emissionregion that reflects light of wavelength λ, be adjusted so that thefollowing relationships are satisfied.

 L=Σdi

Σ(ni·di)=m·λ/2  Eq. 2

where, in Equation 2, ni is the refractive index of each layer existingbetween the reflecting surface on the negative electrode side of thereflecting layer 7 and the reflecting surface on the negative electrodeside of the semi-reflecting layer 2, di is the thickness thereof, and mis a natural number.

The reflecting layer group 7 is positioned at the back surface of thenegative electrode 5, configured with reflecting layers 7R, 7G, and 7Bthat respectively reflect light having specific wavelengths in the lightthat is emitted through the negative electrode 5 to the back surfacelaminated, ordered in a plane perpendicular to the light axis, incorrespondence with the wavelength of the light to be reflected. Thereflecting layer 7R is optimized so that it interferes with redwavelengths (near 625 nm). The reflecting layer 7G is optimized so thatit interferes with green wavelengths (near 525 nm). And the reflectinglayer 7B is optimized so that it interferes with blue wavelengths (near450 nm).

In the reflecting layer group 7, the reflecting layer 7R that isresonant for light of longer wavelength (red light) is positionedclosest to the negative electrode 5, while the reflecting layers 7G and7B that are resonant for light of shorter wavelength (green and bluelight) are arranged so that they line up in that order. Light of shortwavelength is not easily reflected by semi-reflecting layers optimizedfor light of longer wavelength, wherefore an efficient reflecting mirrorcan be configured by ordering the layers in this fashion.

The reflecting layer group 7 in this embodiment is configured so thatmultiple types of reflecting layer are separated between light emissionregions or defined specifically for each light emission region. This isdone because light emitting layers corresponding to each, color areformed at different positions in order to adjust the light emissionconditions on the front surface side in the light emitting layer 4. Thisis so because, since it is necessary to adjust the light emissionconditions on the back surface side independently, as for the frontsurface side, the reflecting layer group 7 must be separated and movedaccording to light emission region. However, so long as the optical pathlength conditions can be satisfied, it is not absolutely necessary toform these separated. In other words, if the optical path length betweenthe reflecting surfaces on the light emitting layer side in thereflecting layers in the reflecting layer group and the reflectingsurfaces on the light emitting layer side in the semi-reflecting layersin the semi-reflecting layer group can be adjusted so that resonance canbe achieved for wavelengths in any light emission region, it is possibleto form the reflecting layers continuously in all of the light emissionregions.

In FIG. 2 is given an enlarged diagram of the layer structure in thereflecting layers in the reflecting layer group 7 for explaining theinterference conditions. Each reflecting layer is made by alternatelystacking two layers having different refractive indexes, namely a firstlayer 71 and a second layer 72. In terms of the interference conditionsfor refractive index and thickness, adjustments are made so that thefollowing relationship is satisfied.

n ₁ ·d ₁ ≈n ₂ ·d ₂≈(¼+m/2)·λ  Eq.3

where n₁ is the refractive index for the first layer 71, d₁ is thethickness thereof, n₂ is the refractive index for the second layer 72,d₂ is the thickness thereof, λ is the wavelength of light reflected inthat reflecting layer, and m is an integer 0 or greater. The thicknessof the two layers corresponds to the half wavelength of light.Reflection occurs when light is transmitted from a layer of lowrefractive index to a layer of high refractive index, wherefore it isdesirable that the arrangement be such that, beginning from the negativeelectrode side, there are a layer of high refractive index, a layer oflow refractive index, a layer of high refractive index, and a layer oflow refractive index, set such that

n ₁ >n ₂.

In terms of specific materials for the reflecting layers 7R, 7G, and 7B,dielectric materials of different refractive indexes are stacked up sothat the relationship in Equation 3 is satisfied. An example would bethe use of TiO₂ having a refractive index of 2.4 for the first layer 71and SiO₂ having a refractive index of 1.44 for the second layer 72. Analternative example would be the use of ZnS having a refractive index of2.37 for the first layer 71 and MgF₂ having a refractive index of 1.38for the second layer 72. The layers configuring the reflecting layersare not limited to dielectric substances, however, and may have alaminar structure made up of a resin and a liquid crystal as cited inJapanese Patent Application Laid-Open No. H10-133222/1998 (gazette). Inthe reflecting layers, the thicknesses of the first and second layers,respectively, are adjusted so as to agree with the wavelengths in thosereflecting layers. When the difference in refractive index between thefirst and second layers is small, the reflectance will be low, so manylayers are laminated.

There is no limitation on the configuration on the front surface side ofthe organic electro-luminescence light emitting device but, in thisembodiment, a micro resonance structure is provided similar to theconfiguration on the back surface side.

The positive electrode 3 is provided so as to exhibit lighttransmissivity and to function as the positive electrode in the organicEL device, and the material used therefore is a metal, alloy, orelectrically conductive compound having a large work function (4 eV orgreater), or mixture thereof. ITO may be cited as preferable, and, ifthey are made thin enough to secure light transmissivity, other metalssuch as Au, or CuI, SnO₂, or ZnO, may be used.

The thickness of the positive electrode 3 is formed similarly with theresonance conditions adjusted in the gap adjustment layer 6 on the backsurface side.

The semi-reflecting layer group 2 comprises the semi-reflecting layers2R, 2G, and 2B. The configuration in each semi-reflecting layer 2R, 2G,and 2B may be considered to be like the configuration in the reflectinglayers 7R, 7G, and 7B. In other words, they are configured with a firstlayer and a second layer of different refractive index alternatelystacked up. However, the relative position of the light emitting layer 4is reversed, wherefore the order of stacking is the reverse of that inthe reflecting layer group 7.

The substrate 1 provides a base during fabrication. It is made of amaterial that exhibits light transmissivity and a certain degree ofmechanical strength, environmental protection, and that can withstandheat treatment during fabrication. Glass, quartz, and resins aresuitable for this material.

In the configuration described in the foregoing, the negative electrode5 transmits a portion of the light ejected from the light emitting layer4 to the back surface. The light that passes through the negativeelectrode 5 proceeds to the reflecting layer group 7. The gap adjustmentlayer 6 determines, for the light in each light emission region, theoptical path length between the reflecting surface in the reflectinglayer in the reflecting layer group and the reflecting surface in thesemi-reflecting layer in the semi-reflecting layer group. The reflectinglayer group 7 is made so that each of its reflecting layers 7R, 7G, and7B, respectively, can reflect light of the corresponding color, and sothat the resonance conditions between the reflecting surfaces aresatisfied. In each light emission region, only light corresponding tothat light emission region is reflected by the reflecting layer,whereupon that light passes again through the negative electrode 5 andreaches the light emitting layer 4. Some of the light that is ejectedfrom the light emitting layer 4 to the front surface is reflected at thesemi-reflecting layer in the semi-reflecting layer group and returned tothe light emitting layer side. For this reason, light resonance occursbetween the reflecting surfaces of the reflecting layers and thereflecting surfaces of the semi-reflecting layers. When the thickness ofthe negative electrode 5 is adjusted here so that phases of the lightreflected from the front surface and of the light reflected from theback surface coincide, the light spectrum is sharpened by the resonance,and the light is intensified and ejected from the light emitting deviceto the outside.

In order to employ this multiple-wavelength light emitting device in anelectronic apparatus, a drive circuit is configured and connectedthereto so that control voltages can be applied independently, in lightemission region units, across the positive electrode and the negativeelectrode. If the drive circuit is driven according to pixel on and offstates for displaying image data and control voltages are appliedaccordingly to each light emission region, the light-emitting pixel(reflection) regions and the non-light-emitting pixel regions willfluctuate according to the image data, wherefore an overall colordisplay can be effected.

As based on the first embodiment described in the foregoing, lightleaking out to the back surface of the negative electrode is mutuallyintensified under optimum conditions between a reflecting layer on theback surface side and a semi-reflecting layer on the front surface side,thereby making it possible to provide a multiple-wavelength lightemitting device exhibiting good light emission efficiency.

As based on this embodiment, furthermore, a reflecting layer optimizedfor light of long wavelength is provided, wherefore efficiency can beimproved without affecting the light of other wavelengths.

As based on this embodiment, moreover, an organic EL device is used asthe light emission means, wherefore it is possible to select from amonga wealth of materials for material exhibiting suitable wavelengthdispersion.

As based on this embodiment, furthermore, the light-emitting-material ischanged among light emission regions, wherefore light of higher purityand greater intensity can be output.

As based on this embodiment, moreover, light is allowed to pass throughthe negative electrode, wherefore the range of selectable materials isbroadened.

Embodiment 2

In the first embodiment described in the foregoing, different lightemitting layers are provided for each light emission region. In a secondembodiment, a common light emitting layer is provided for all of thelight emission regions. In FIG. 3 is diagrammed the layer structure ofthe multiple-wavelength light emitting device in the second embodiment.This multiple-wavelength light emitting device, as diagrammed in FIG. 3,comprises a substrate 1, a semi-reflecting layer group 2, a positiveelectrode 3, a light emitting layer 4 b, a negative electrode 5, a gapadjustment layer 6, and a reflecting layer group 7.

The characteristic feature of this embodiment is that a light emittinglayer 4 b is provided in common for all of the light emitting regions.As the material for such a light emitting layer 4 b, it is preferable touse a broad spectral-range light emitting material containing thewavelength components of the light supplied from each light emissionregion in good balance. Such materials that can be used include aluminumchelate (Alq₃), and polyparaphenylene vinylene, etc.

The other configurational aspects and optical conditions may beconsidered to be the same as in the first embodiment already described.In cases where the electric charge carrying capability of the lightemitting layer is poor, it is permissible to incorporate a holeinjection layer or a hole transport layer and/or an electron transportlayer as in an embodiment described subsequently.

In the configuration described above, light containing all of thewavelength components to be output is ejected to the back surface. Inthe reflecting layer group 7, at each reflecting layer is reflectedlight having a wavelength optimized to that reflecting layer. However,the distance between the reflecting surface on the light emitting layerside of the semi-reflecting layer and the reflecting surface in eachreflecting layer is optimized so as to coincide with resonanceconditions only for light of one light emission region, wherefore onlylight having a wavelength coinciding with those resonance conditionswill have its spectrum sharpened and be reflected.

As based on the second embodiment described above, while displaying thesame effectiveness as in the first embodiment described earlier, it isnot necessary to fabricate light emitting layers separately for eachlight emission region, wherefore fabrication is simplified.

Embodiment 3

A third embodiment of the present invention relates to a configurationwherein an electron transport layer is added to the organic EL device ofthe embodiments described earlier.

In FIG. 4 is diagrammed a layer structure of the multiple-wavelengthlight emitting device in the third embodiment. This multiple-wavelengthlight emitting device, as diagrammed in FIG. 4, comprises a substrate 1,a semi-reflecting layer group 2, a positive electrode 3, a lightemitting layer 4, an electron transport layer 8, a negative electrode 5,a gap adjustment layer 6, and a reflecting layer group 7.

The electron transport layer 8, also called an electron injection layer,exhibits the function of efficiently transferring electrons injectedfrom the negative electrode to the light emitting layer. For thiselectron transport layer it is possible to use the materials cited ineither Japanese Patent Application Laid-Open No. H10-163967/1998,H8-248276/1996, or S59-194393/1984. More specifically, it is possible touse a nitro-substitution fluorene derivative, an anthraquino-dimethanederivate, a difenyl quinone derivative, a thiopyrane-dioxide derivative,a heterocyclic tetracarboxylic acid anhydride such as naphthaleneperilene, carbodiimide, a freoledine methane derivative, a derivative ofanthraquino-dimethane and anthrone, an oxadiazole derivative, or aquinoxaline derivative. The thickness thereof is made sufficient toexhibit an electron carrying function.

The electron transport layer may be present or absent, and whether ornot to provide it may be determined in conjunction with the organic ELmaterial.

A hole transport layer may be provided between the light emitting layer4 and the positive electrode 3. For the hole transport layer is usedeither an organic or inorganic substance that exhibits a hole injectionfunction and/or an electron obstructing function. Those substances citedin Japanese Patent Application Laid-Open No. H10-163967/1998 or No.H8-248276/1996 can be used for this purpose.

The layer structure otherwise is the same as in the first embodimentdescribed earlier and so is not further described here.

As based on the third embodiment described above, while displaying thesame effectiveness as in the first embodiment described earlier, anelectron transport layer is provided, wherefore the light emissionefficiency of the organic EL device is enhanced, making it possible toproduce a light emitting device that is even brighter.

Embodiment 4

A fourth embodiment of the present invention relates to a configurationwherein the thickness of the negative electrode is changed for eachlight emission region. The layer structure of the multiple-wavelengthlight emitting device that is the fourth embodiment is diagrammed inFIG. 5. This multiple-wavelength light emitting device, as diagrammed inFIG. 5, comprises a substrate 1, a semi-reflecting layer group 2, apositive electrode 3, a light emitting layer 4, a negative electrode 5b, a gap adjustment layer 6 b, and a reflecting layer group 7.

The negative electrode 5 b differs from the negative electrode 5 in thefirst embodiment in that the thickness thereof is adjusted so that thesurface on the reflecting layer group 7 side is in the same plane in alllight emission regions. The gap adjustment layer 6 b differs in that thethickness thereof has been changed from that of the gap adjustment layer6 in the first embodiment in order to match the resonance conditions ineach light emission region, due to the fact that the position of thesurface on the reflecting layer group 7 side in the negative electrode 5b has changed. The configuration in other respects is the same as in theembodiments described in the foregoing. As in the second and thirdembodiments described earlier, a hole transport layer and/or an electrontransport layer may be provided, and the light emitting layer may bemade common for all of the light emission regions.

As based on the fourth embodiment described above, the surface of thenegative electrode 5 b on the reflecting layer group 7 side is formed inone plane, thus affording the advantage of making fabrication of boththe gap adjustment layer 6 b and the reflecting layer group 7 easier.

Embodiment 5

In the embodiments described in the foregoing, the resonance conditionsare established by making the thickness of the gap adjustment layerdifferent for each light emission region. In a fifth embodiment, theresonance conditions are altered while keeping the thickness of eachlayer uniform.

In FIG. 6 is diagrammed the layer structure for the multiple-wavelengthlight emitting device in the fifth embodiment. This multiple-wavelengthlight emitting device comprises, as diagrammed in FIG. 6, a substrate 1,a semi-reflecting layer group 2, a positive electrode 3, a lightemitting layer 4, a negative electrode 5 b, and reflecting layers 7R,7G, and 7B provided with spacers 9R, 9G, and 9B, respectively. Thecharacteristic feature of the multiple-wavelength light emitting devicein this embodiment is that the reflecting layers are uniformly acrossall of the light emission region.

The positive electrode 3, light emitting layer 4, and negative electrode5 are all formed with a uniform thickness across the light emissionregions.

The semi-reflecting layer group 2 comprises spacers 10B and 10G betweenthe semi-reflecting layers. The spacer particulars may be considered tobe the same as for the spacers 9G and 9B described below.

The materials for the light emitting layer 4 are selected, respectively,so that they contain large amounts, respectively, of red lightwavelength components in the light emitting layer 4R in the red lightemission region A_(R), of green light wavelength components in the lightemitting layer 4G in the green light emission region A_(G), and of bluelight wavelength components in the light emitting layer 4B in the bluelight emission region A_(B), while containing comparatively smallamounts of other wavelength components therein. That is because, in thisembodiment, the layer structure is the same for every light emissionregion, wherefore it is necessary to specify the light emissionwavelength with the characteristics of the light emitting layer itself.

The negative electrode 5 b is adjusted, as in the fourth embodiment, sothat the surface on the reflecting layer group side is in the same planein all light emission regions. This is made an even surface in order tofacilitate fabrication of the laminar structure on the back surfaceside.

The spacer 9R is a layer the thickness whereof is set to be even in alllight emission regions. It is a layer for adjusting the gap in the redlight emission region so as to satisfy the resonance conditions. Thespacers 9G, 9B, 10B, and 10G are layers for adjusting the gap betweenthe reflecting layer layers so that the resonance conditions aresatisfied in the other light emission regions.

The material used for the spacers should be a material that exhibitshigh light transmissivity and that bonds well with the semi-reflectinglayers, such, for example, as a resin or a dielectric. If it is possibleto maintain the distance between the semi-reflecting layers, then ofcourse this layer may even be made of a gas, liquid, or liquid crystal.The materials used in the spacers 9G, 9B, 10B, and 10G may also be madedifferent so that the refractive indexes thereof are different.

The thicknesses of the spacers 9R, 9G, 9B, 10B, and 10G are set so as tomatch the resonance conditions described for the first embodiment. Morespecifically, for the red light emission region A_(R), the optical pathlength L_(R) between the reflecting surface in the reflecting layer 7Rand the reflecting surface on the light emitting layer side of thesemi-reflecting layer 2R is maintained so as to correspond with anatural number multiple of the half wavelength of the light (red light)reflected in that reflecting layer 7R. In Equation 2 given above, whichrepresents the resonance conditions, to the optical path length whenthere is no spacer is added an optical path distance corresponding tothe product of the refractive index n_(9R) of the spacer 9R and thethickness D_(9R) thereof (i.e. n_(9R)·D_(9R)). For the green lightemission region A_(G), the sum of the optical path distancecorresponding to the product of the spacer 9G refractive index n_(9G)and the thickness thereof D_(9G), the optical path distancecorresponding to the product of the spacer 10G refractive index n_(10G)and the thickness thereof D_(10G), and the optical path distance in thespacer 9R (i.e. n_(9R)·D_(9R)+n_(9G)·D_(9G)+n_(10G)·D_(10G)) is added tothe optical path length when there is no spacer, and the thickness thusset so as to satisfy the resonance conditions represented by Equation 2.For the blue light emission region A_(B), the optical path lengths forthe spacers 9R, 9G, 9B, 10G, and 10B (i.e.n_(9R)·D_(9R)+n_(9G)·D_(9G)+n_(9B)·D_(9B)+n_(10G)·D_(10G)+n_(10B)·D_(10B))are added to the optical path length when there is no spacer, and thethickness thus set so as to satisfy the resonance conditions in Equation2.

In cases where the electrical charge carrying capacity of the lightemitting layer is low, moreover, either a hole transport layer or anelectron transport layer, or both, may be provided.

In the configuration described in the foregoing, the light from thelight emitting layer passes through the negative electrode 5 b and isalso ejected to the back surface, whereupon red light resonates as inthe first embodiment between the reflecting surface of the redreflecting layer 7R closest to the light emitting layer and thereflecting surface with the red semi-reflecting layer 2R on the frontsurface side and is reflected efficiently. In the other light emissionregions also, the optical path length between the reflecting layers andthe semi-reflecting layers is adjusted to coincide with a natural numbermultiple of the half wavelength, wherefore resonance occurs for thelight of those respective wavelengths, and the resonant wavelengthspectrums are sharpened and reflected efficiently.

As based on the fifth embodiment described in the foregoing, whiledisplaying the same effectiveness as in the first embodiment describedearlier, both the spacers and the reflecting layers need only be formedwith a flat, even thickness, wherefore such complex process steps aspatterning can be omitted and fabrication costs lowered.

Embodiment 6

A sixth embodiment relates to a modification of the gap adjustmentmethod employed in the fifth embodiment. In FIG. 7 is diagrammed thelayer structure of the multiple-wavelength light emitting device in thesixth embodiment.

This multiple-wavelength light emitting device comprises, as diagrammedin FIG. 7, a substrate 1, a semi-reflecting layer group 2, a positiveelectrode 3, a light emitting layer 4, a negative electrode 5 b, andreflecting layers 7R, 7G, and 7B in contact with the gap adjustmentlayer 74R and the gap adjustment layer 74G and the gap adjustment layer74B. The characteristic feature of the multiple-wavelength lightemitting device in this embodiment is that the reflecting layers arepositioned uniformly without being separated between the light emittingregions, as in the fifth embodiment.

The positive electrode 3, light emitting layer 4, and negative electrode5 are formed of uniform thickness across all of the light emissionregions.

The gap adjustment layer 74R can be considered to be the same as the gapadjustment layer 6 described earlier. However, it is possible to use thesecond layer 72 having lower refractive index in the red reflectinglayer 7R as the gap adjustment layer 74R. The gap adjustment layer 74Gis a layer for adjusting the gap between the reflecting layers, in aconfiguration wherein the thickness of the second layer 72 having a lowrefractive index closest to the reflecting layer 7G, of the red lightreflecting layer 7R, has been altered. The gap adjustment layer 74B is alayer for adjusting the gap between the reflecting layers, in aconfiguration wherein the thickness of the second layer 72 having a lowrefractive index closest to the reflecting layer 7B, of the green lightreflecting layer 7G, has been altered.

Because the layers comprising the reflecting layers are themselvesdielectric materials, if the thickness of one layer thereof is madedifferent, that layer will cease to be a layer that contributes to lightinterference, and will contribute to increasing the optical path lengthprovided by the refractive index and thickness thereof.

The thickness of the gap adjustment layer 74G, for green light, is setso that the optical path length corresponding to the product of therefractive index (given as n₂) of the gap adjustment layer 74R and thethickness D_(74R) thereof and the optical path length corresponding tothe product of the refractive index n₂ of the gap adjustment layer 74Gand the thickness D_(74G) thereof satisfy the resonance conditionsconsidered in Equation 2. The thickness of the gap adjustment layer 74B,for blue light, is set so that the optical path lengthn₂·(D_(74R)+D_(74G)+D_(74B)) resulting from the gap adjustment layers74R, 74B, and 74G also satisfies the resonance conditions considered inEquation 2.

Furthermore, in the semi-reflecting layer-group 2 also, as in thereflecting layer group 7, it is possible to use some of the layersconfiguring the semi-reflecting layers 2R, 2G, and 2B as gap adjustmentlayers, adjusting the optical path lengths and setting [them] so thatthe resonance conditions are satisfied.

Otherwise the configuration is the same as that in the fifth embodimentdescribed earlier.

As based on the sixth embodiment described in the foregoing, gaps areadjusted with layers at the boundaries of the reflecting layers,wherefore the number of materials used can be reduced, so that, whenforming the gap adjustment layers in the reflecting layer fabricationprocesses, only film thickness control need be implemented, making itpossible to reduce the number of fabrication steps.

Embodiment 7

A seventh embodiment relates to a light emitting device wherein thereflectance of the negative electrode itself is enhanced. In FIG. 8 isdiagrammed the layer structure of the multiple-wavelength light emittingdevice in the seventh embodiment. This multiple-wavelength lightemitting device, as diagrammed in FIG. 8, comprises a substrate 1, asemi-reflecting layer group 2, a positive electrode 3, a light emittinglayer 4, and a negative electrode 5 c.

The negative electrode 5 c, while exhibiting a work function such thatit can be used as the negative electrode in an organicelectro-luminescence device, is made of a material that also exhibitshigh reflectance. This material may be selected from among diamond,boron nitride, and aluminum nitride.

As methods of fabricating a diamond negative electrode, there aremethods for growing a carbon crystalline structure such as a plasma CVDmethod and hot-filament CVD method. It is possible, for example, to formdiamond thin films by chemical-vapor-phase growing carbon crystals froma gas mixture of CH₄+H₂ in an atmosphere at 0.1 Torr and several hundreddegrees.

For boron nitride or aluminum nitride negative electrodes, it ispossible to employ a plasma CVD method capable of forming nitrides bythe CVD method.

As based on this seventh embodiment, the material of which the negativeelectrode is made, while exhibiting a low energy level and thus capableof being used as the negative electrode in a electro-luminescencedevice, also exhibits high reflectance, making it possible to improvethe light utilization factor.

Other Modifications

The present invention is not limited to or by the embodiments describedin the foregoing but can be configured with suitable modifications solong as the main concept thereof is retained. The reflecting layersbased on multi-layer dielectric materials, for example, are onlyemployed herein as representative reflecting means capable of thin-filmformation; any known thin film having a reflecting function but someother structure may be used instead.

In the embodiments described in the foregoing, multi-layer dielectricfilms are used for the reflecting layers, but this is not a limitation.It is permissible, for example, to employ optical elements functioningas half mirrors or thin films, installing them so as to satisfy theresonance conditions, or to employ polarizing panels as the reflectinglayers, controlling the light polarizing conditions.

The light emission means are not limited to an organicelectro-luminescence device either, but may be some other light emissionmeans based on another light emission effect.

There is no limitation on the electronic apparatus in which it ispossible to employ the multiple-wavelength light emitting device of thepresent invention. It can be used in display devices or illuminationdevices in watches, calculators, portable telephones, pagers, electronicnotebooks, notebook PCs, and other portable information terminaldevices, and also in camera viewfinders and large displays.

As based on the present invention, multiple-wavelength light emittingdevices can be provided which can emit light in a plurality ofwavelengths with higher efficiency than conventionally because thestructure thereof makes it possible to reflect light that leaks out tothe back surface back to the front surface under ideal conditions.

As based on the present invention, multiple-wavelength light emittingdevices can be provided which exhibit a higher. efficiency for aplurality of wavelengths more efficiently than conventionally, becauseunder the ideal conditions, the structure thereof makes it possible tolight leaks out to the back surface towards front surface.

As based on the present invention, it is possible to provide electronicapparatus capable of brighter displays than conventionally because theycomprise multiple-wavelength light emitting devices that emit light in aplurality of wavelengths with higher efficiency than conventionally.

What is claimed is:
 1. A multiple-wavelength light emitting device foremitting light in a plurality of different wavelengths, comprising:light emission means for emitting light containing wavelength componentsto be output; a semi-transparent layer that transmits at least a portionof said light, placed at the back surface of said light emission means;a reflecting layer group provided on a first surface side of said lightemission means, with said semi-transparent layer intervening, whereinreflecting layers that reflect light have specific wavelengths of lightejected to said first surface side from said light emission means viasaid semi-transparent layer are laminated in order in the direction oflight axis in correspondence with wavelengths of light to be output; anda semi-reflecting layer group, provided on a second surface side inopposition to said first surface of said light emission means, formed bylaminating multiple types of semi-reflecting layers each lavercorresponding to a different wavelengths of reflected light out ofmultiple different wavelengths, wherein semi-reflecting layers thatreflect a portion of light having specific wavelengths of light ejectedto said second surface side from said light emission means and transmitthe remainder thereof are laminated in order in the direction of saidlight axis in correspondence with wavelengths of light to be output;wherein: in two or more light emission regions wherein output lightwavelength differs, the distance between the reflecting surface forlight from said light emission means in a reflecting layer in saidreflecting layer group that reflects light of wavelength output in thatlight emission region and the reflecting surface for light from saidlight emission means in a semi-reflecting reflecting layer in saidsemi-reflecting layer group that reflects a portion of light ofwavelength output in that light emission region is adjusted so that itbecomes a resonating optical path length for light ejected from thatlight emission region.
 2. The multiple-wavelength light emitting deviceaccording to claim 1, wherein the thickness of said semi-transparentlayers is adjusted so that the phase of light that, after beingreflected by said reflecting layer group, again passes through thatsemi-transparent layer and is ejected to said second surface side ofsaid light emission means coincides with the phase of light that isdirectly ejected to said second surface side of said light emissionmeans.
 3. The multiple-wavelength light emitting device according toclaim 2, wherein a relational adjustment is made so that  Σ(ni·di)=m·λ/2is satisfied, where, in a light emission region wherein light ofwavelength λ is ejected, ni is the refractive index in each layer thatexists between the point of light emission in said light emission meansand the light reflecting surface of the light reflecting layer for lightof wavelength λ in said light reflecting layer group, di is thethickness thereof, and m is a natural number.
 4. The multiple-wavelengthlight emitting device according to claim 1, wherein a gap adjustinglayer is provided between said semi-transparent layer and saidreflecting layer group for adjusting the distance between the reflectingsurface for light from said light emission means in said lightreflecting layers and the reflecting surface for light from said lightemission means in said semi-reflecting layers.
 5. Themultiple-wavelength light emitting device according to claim 1, whereinsaid reflecting layer group is configured with multiple types ofreflecting layer corresponding to wavelengths of multiple kinds of lightof different wavelength separated between said light emission regions.6. The multiple-wavelength light emitting device according to claim 1,wherein reflecting surfaces for light from said light emission means insaid reflecting layers in said reflecting layer group are located atdifferent positions in the thickness dimension for each light emissionregion.
 7. The multiple-wavelength light emitting device according toclaim 1, wherein, in a light emission region where light of wavelength λis ejected, the distance L between a reflecting surface for light fromsaid light emission means in the reflecting layer that outputs light ofwavelength λ and the reflecting surface for light from said lightemission means in said semi-reflecting layer is relationally adjusted sothat L=Σdi Σ(ni·di)=m·λ/2 are satisfied, where ni is the refractiveindex of the i'th substance between these reflecting surfaces, di is thethickness thereof, and m is a natural number.
 8. The multiple-wavelengthlight emitting device according to claim 1, wherein, in said reflectinglayer group, reflecting layers reflecting light of longer wavelength areplaced on said light emission means side.
 9. The multiple-wavelengthlight emitting device according to claim 1, wherein reflective layersmaking up said reflecting layer group are configured so that two layersof different refractive index are alternately stacked up.
 10. Themultiple-wavelength light emitting device according to claim 9, whereinsaid reflecting layers are adjusted so that the relationshipn1·d1≈n2·d2≈(¼+m/2)·λ is satisfied, where n1 is the refractive index ofone layer of said two layers having differing refractive indexes, d1 isthe thickness thereof, n2 is the refractive index of other layer, d2 isthe thickness thereof, λ is the wavelength of light reflected in thatreflecting layer, and m is 0 or a natural number.
 11. Themultiple-wavelength light emitting device according to claim 1, whereinsurfaces on said reflecting layer group side of said semi-transparentlayers are formed so that they are in the same plane in all lightemission regions.
 12. The multiple-wavelength light emitting deviceaccording to claim 1, wherein said reflecting layer group is such thatmultiple types of reflecting layers corresponding to wavelengths oflight of multiple different wavelengths are laminated uniformly withoutbeing separated between light emission regions.
 13. Themultiple-wavelength light emitting device according to claim 1, whereinsaid reflecting layer group is such that spacers are provided betweensaid reflecting layers for adjusting the optical path length between thereflecting surface for light from said light emission means in saidreflecting layer and the reflecting surface for light from said lightemission means in said semi-reflecting layer.
 14. Themultiple-wavelength light emitting device according to claim 9, whereinsaid reflecting layer group is such that, in order to adjust the opticalpath length from the reflecting surface for light from said lightemission means in said reflecting layers to the reflecting surface forlight on said light emission means side in said semi-reflecting layers,the thickness of any one layer in the laminar structure of layers havingdifferent refractive indexes configuring said reflecting layers isaltered.
 15. The multiple-wavelength light emitting device according toclaim 1, wherein a plurality of types of light emission means foremitting relatively many light components having wavelengths associatedwith said light emission regions are provided so as to correspond withsaid light emission regions.
 16. The multiple-wavelength light emittingdevice according to claim 1, wherein light emission means capable ofemitting light having wavelength components associated with all of saidlight emission regions is provided in common for said light emissionregions.
 17. The multiple-wavelength light emitting device according toclaim 1, wherein said light emission means are an organicelectro-luminescence layer sandwiched between electrodes, with theelectrode provided at the first surface thereof being made saidsemi-transparent layer.
 18. The multiple-wavelength light emittingdevice according to claim 17, wherein said light emission means comprisean electron transport layer and/or a hole transport layer.
 19. Anelectronic apparatus comprising a multiple-wavelength light emittingdevice cited in claim
 1. 20. A multiple-wavelength light emitting devicefor emitting a plurality of light types having different wavelengths,comprising: an organic electro-luminescence layer for emitting lightcontaining wavelength components to be output; an electrode forreflecting light ejected to a first surface of said organicelectro-luminescence layer, positioned at said first surface of saidorganic electro-luminescence layer; wherein: said electrode isconfigured of one substance selected from a group made up of diamond,boron nitride, and aluminum nitride; and a semi-reflecting layer groupformed by laminating multiple types of semi-reflecting layers, eachlayer corresponding to a different wavelengths of reflected light out ofmultiple different wavelengths.